Corrosion preventing compositions



United States Patent 3,510,440 CORRQSION PREVENTING COMPOSITIONS RobertEdward Campbell, Doncaster, England, assignor to British Ropes Limited,Doncaster, England, a British company No Drawing. Filed Oct. 18, 1965,Ser. No. 497,478 Claims priority, application Great Britain, Dec. 1,1964,

48,711 Int. Cl. C09d /08 US. Cl. 260-23 27 Claims ABSTRACT OF THEDISCLOSURE Thin flakes of platelets of organic or inorganic material arefirst mixed with smaller sized lead or tin containing particles andmilled so as to produce a thin continuous lead or tin containing filmcompletely encapsulating the flakes. The coated flakes then aredispersed in a medium which at room temperaure is viscous and p0-lymerizable and the composition used to coat wire, wire strands or Wireropes to protect the same against corroslon.

This invention relates to corrosion preventing compositions moreespecially for use for protecting wire, wire strands or wire ropes fromcorrosion.

The metal lead and certain of its alloys, are noteworthy for theirchemical inertness over a wide range of corrosive environments. However,the employment of such materials has, in the past, been considerablylimited because of the following aspects:

(a) The high intrinsic cost.

(b) High specific gravity and consequent ditficulty in maintainingparticulate dispersions in a satisfactory state prior to, and during,their application.

(0) Difiiculty in finding an effective dispersive agent, embodyingelastomeric qualities.

The present invention consists in a corrosion preventing compositioncomprising a dispersive medium and particulate material in thedispersive medium, in which the particulate material is provided with acoating of lead or a lead alloy or tin or a tin alloy.

The specific gravity of the dispersive material may be about 1.1, with apossible variation of some 25% either way.

The particulate material itself may be selected from a wide range ofmaterials cheaper than lead and its specific gravity may be such as toensure good suspension on the dispersive material.

Prior to adding the particulate material to the dispersive medium, it isnecessary to apply simply and cheaply a thin, homogeneous film of leador a selected alloy to the entire surface of the particles forming theparticulate material.

Preferably the particulate material is in the form of thin flakes orplatelets and the following are the preferred materials for theseplatelets:

(i) Metal: aluminium or its alloys magnesium or its alloys (ii) Organicpolymer: polyvinyl chloride, polyethylene, polypropylene, nylon, or thelike (iii) Inorganic material: mica, asbestos, vermiculite, or micaceousiron ore processed to a suitable condition and size that it will passthrough a 200 mesh sieve.

If an uncoated particulate material from category (i) is employed, itsgravity will be such that it will tend to settle in the dispersivemedium. However, if a material from category (ii) is employed, thespecific gravity can range from as low as 0.90 to as high as 2.20;consequently, it is possible to select a material which will remain insuspension, even when coated with a thin film of metal such as lead.Likewise, the materials listed in category (iii) permit a similarcombination.

It will be seen that by careful selection of the particulate agent, itis possible to exercise a much greater control in maintaining theencapsulated particles in a state of suspension. This would preventexcessive settlement in storage containers, a normally serious problemwith metallic dispersions. It can also offer advantages in use, as abetter dispersion of the particulate material is obtained as the solventcontent evaporates.

As a dispersive medium, there may be used any synthetic resinousmaterial which, at room temperature, is a viscous fluid capable ofcontrolled progressive polymerisation by blending with a suitableproportion of a reactive intermediate; specific examples of such anintermediate are (a) benzoyl peroxide, (b) an oil of vegetable originsuch as linseed oil, or any oil possessing drying, or semi-dryingproperties.

Alternatively, materials of animal origin, which are capable ofpolymerisation, such as lanolin, may be employed. Such a mixturesubsequently reacts to produce certain desirable physical and chemicalcharacteristics.

A specific example of a mixture generically of this type is Grade R302,manufactured by Bakelite Limited. Grade R302 is an amber colored viscousliquid which flows slowly at 20 C. and comprises an oil modified heathardening phenolic resin having a specific gravity at 25/25 C. of 0.98.Its viscosity at 25 C. diluted 2:1 wt./wt. with toluene is centistokes.It has an acid value of 34 mg. KOH/ g. and is soluble in benzene,toluene, xylene and drying oils.

Preferably the particulate material is milled together with the coatingagent in the ratio of 2-15 of coating agent by weight per unit weight ofparticulate material.

A suitable particle size for the lead particles to be milled to form thesurface coating is dust to 100 mesh with 0-200 mesh preferred.

The preferred metal for the coating material is lead. Small additions oftin would improve the toughness of the metallic film without destroyingits smear capacity, whilst antimony could materially improve thehardness.

The minimum amount of coating metal is that which will produce a thin,but continuous, film to completely envelop the supporting agent, andthis should not be less than 2% volume/ volume.

Regarding the maximum amount, there does not appear to be any technicaladvantage in exceeding 10% volume/volume, where a pure coating metal isinvolved, although alloying agents might permit the employment of aslightly higher percentage.

The optimum percentage lies in the region of 5% of coating metal to ofsupporting agent, volume/volume.

The actual operation of encapsulation is two-fold in that dust particlesof the selected metal adhere to the surface of the supporting elastomer,or inorganic material, and, due to their small size, are capable ofdeformation and smearing with very light pressure; there is also thepossibility of electro-static attraction. Simultaneously, the largerparticles of metal are impressed into the surface of the supportingmedium and, once mechanically an chored, the exposed surfaceirregularities are plastically deformed and smeared together by themilling operation.

The most positive method of checking is by a colourmacroscopictechnique.

The colour check is achieved by employing a reagent which forms abrightly coloured, or distinctive, pigment when it reacts with theselected encapsulating metal or alloy. Then follows the macroscopicexamination of a suflicient quantity of the material to ensure thatencapsulation of the particles has been complete, and that the metallicagent has truly coated the supporting material, and not merely formed adry dispersion.

For example, nylon powder has a white, almost crystalline appearance,but after milling has a grey appearance. If it is then treated withacidified Potassium Dichromate and elutriated with water, a continuousbright yellow film forms over all the particles, and proves quitereadily that complete encapsulation has been achieved.

The same technique applies when aluminum is encapsulated with lead.

The milling operation may be carried out by employing a ball mill, anend runner mill, or any such device which will produce a thin,continuous coating.

The final operation-to produce the requisite protective and lubricatingcompound is to disperse the composite metal-flake in the preferredsynthetic resin base by any appropriate means, usually in the presenceof a small amount of organic solvent which facilitates the mixingoperation. When the formulation is subsequently applied to a metalsurface, in the presence of air, the solvent is lost by evaporation.

Protective coatings applied in the manner described will give indefiniteprotection to ferrous surfaces in both acid and alkaline environments.They are of particular value in the manufacture, and subsequentdressing, of steel wire where the agent required to give protection ofthe wires against corrosion must, at one and the same time, function asa lubricant when the rope is subjected to dynamic loading.

Furthermore, formulations of this nature are extremely stable over awide range of temperatures, and have high adhesive powers. However, theymay when necessary, be readily removed with a suitable solvent mixture,but are readily re-applied by brushing or spraying, thus permittingready inspection and re-sealing of the underlying structure.

Tests have shown that, when the same base resin is employed as thedispersant, that lead encapsulated aluminium flake has a 2% increase inlubricating efficiency, compared with untreated aluminum flake of thesame size.

Preferred sample compositions are as follows:

Percent Range Typical 4o Composition 1:

Lead coated aluminum flake 20-30 24 Resin base 25-35 30 Microcrystallinewax, melting point 140- 170 F 5-10 7 Solvent (white spirit)--. 35-45 39Composition 2: Lead coated magnesium flake 20-30 24 Resin base 25-35 30Microcrystalline wax, melting point 140- 170 F 5-10 7 Solvent (whitespirit) 35-45 39 Composition 3:

Lead coated organic powders in the form form of polymers, e.g.polythene, polypropylene, P.V.C 20-30 24 Resin base 25-35 30Microcrystall' 170 F 5-10 7 Solvent (White spirit) 35-45 39 Composition4:

Lead coated inorganic flake material, e.g.

mica, micaceous iron ore, vermiculite as pigment 20-30 24 Resin base25-35 30 Microcrystalline wax, meltlng point 140- 0 5-10 7 35-45 39 Cornosition 5:

Bead coated zinc powder 20-30 24 Resin base 25-35 30 Microcrystallinewax, melting point 140- 170 F 5-10 7 Solvent (white spirit) 35-45 39Composition 6:

Lead coated zinc powder 82-88 87 Resin base 2. 5-4. 5 3 Microcrystallinewax, melting point F 0. 9-1. 8 0. 5 Solvent (white spirit) 5-15 9. 5

Various modifications may be made in accordance with the invention.

I claim:

1. A particulate organic material comprising thin flakes or plateletsthereof which are coated with a thin homogeneous film of lead or a leadalloy or tin or a tin alloy which completely envelope the flakes orplateets.

2. A corrosion preventing composition comprising thin flakes orplatelets of inorganic material coated with a thin homogeneous film oflead or lead alloy or tin or tin alloy which completely envelopes theflakes or platelets, said coated flakes or platelets being in a viscousfluid comprising oil modified phenolic resin and an evaporable organicsolvent.

3. A corrosion preventing composition comprising thin flakes orplatelets of organic or inorganic material other than lead or tin, saidthin flakes are platelets being individually encapsulated by a thincontinuous coating of lead, lead alloy, tin, or tin alloy, saidencapsulated flakes or platelets being suspended in a dispersive mediumcomprising a polymerizable viscous fluid.

4. A corrosion preventing composition as claimed in claim 3 in which thethin flakes or platelets are metallic particles.

5. A corrosion preventing composition as claimed in claim 4 in which thethin flakes or platelets are aluminium or aluminium alloy particles.

6. A corrosion preventing composition as claimed in claim 4 in which thethin flakes or platelets are magnesium or magnesium alloy.

7. A corrosion preventing composition as claimed in claim 3 in which thethin flakes or platelets are polyvinyl chloride.

8. A corrossion preventing composition as claimed in claim 3 in whichthe thin flakes or platelets are polyethylene.

9. A corrosion preventing composition as claimed in claim 3 in which thethin flakes or platelets are polypropylene.

10. A corrosion preventing composition as claimed in claim 3 in whichthe thin flakes or platelets are particles of inorganic material.

11. A corrosion preventing composition as claimed in claim 10 in whichthe particles are mica.

12. A corrosion preventing composition as claimed in claim 10 in whichthe particles are asbestos.

13. A corrosion preventing composition as claimed in claim 10 in whichthe particles are vermiculite.

14. A corrosion preventing composition as claimed in claim 10 in whichthe particles are micaceous iron ore.

15. A corrosion preventing composition as claimed in claim 14 in whichthe particles are of such a size that will pass through a 200 meshsieve.

16. A corrosion preventing composition as claimed in claim 3 wherein thedispersive medium is oil modified heat hardening phenolic resin.

17. A corrosion preventing composition as claimed in claim 3 in whichthe dispersive medium is a mixture of an oil of vegetable origin and asynthetic resinous material which, at room temperature, is a viscousfluid capable of controlled progressive polymerisation when mixed withthe oil.

18. A corrosion preventing composition as claimed in claim 17 in whichthe specific gravity of the dispersive medium is l.l- -25%.

19. A corrosion preventing composition as claimed in claim 3 in whichthe ratio by Weight of coating agent to flakes or platelets is in therange 2-15%.

20. A corrosion preventing composition as claimed in claim 3 in whichthe volume ratio of coating agent to flakes or platelets is in the range210%.

21. A corrosion preventing composition as claimed in claim 20 in whichthe volume ratio is 5%.

22. Ferrous materials having their surfaces protected by a coatingcomposition as claimed in claim 3.

23. Steel wire ropes having the wire surfaces protected by coatingcompositions as claimed in claim 3.

24. In the process of making a corrosion preventing composition for thetreatment of wire, wire strands and wire ropes, the improvement whereinthin flakes or platelets of organic or inorganic material are firstencapsulated with a thin coating of lead-or tin-containing smaller sizedparticles which is smeared or deformed with light pressure to produce athin continuous film completely enveloping the individual flakes orplatelets and after which the encapsulated flakes or platelets aredispersed in a viscous polymerizable fluid.

25. The process claimed in claim 24 wherein the polymerizable fluidcomprises lanolin.

26. The process claimed in claim 24 wherein the poly- 15 merizable fluidcomprises a synthetic resin which at room temperature is a viscous fluidcapable of controlled progressive polymerization with an oil ofvegetable origin.

27. The process claimed in claim 24 wherein the fluid is polynieri zableby oxidation.

References Cited UNITED STATES PATENTS 3,070,469 12/1962 Jenkin 117l003,316,073 4/1967 Kelso 51309 3,287,142 11/1966 Russell 10614 3,244,6564/1966 de Mejer 260-296 3,003,975 10/1961 Louis 252503 2,939,804 6/ 1960Schossberger 11771 DONALD E. CZAJA, Prmary Examiner D. I. BARRACK,Assistant Examiner U.S. Cl. X.R.

